JP7372178B2 - power supply - Google Patents

Description

The present disclosure relates to a power supply device.

The LLC converter (isolated resonant converter) can reduce switching loss due to ZVS (Zero Voltage Switching) operation and ZCS (Zero Current Switching) operation, and therefore can achieve high efficiency. However, the LLC converter cannot maintain ZVS operation under light loads, resulting in increased switching loss. Therefore, a technique is known that compensates for the switching loss by adding an inductor that stores current for performing ZVS (for example, Patent Document 1 and Patent Document 2).

JP 2018-57223 Publication Japanese Patent Application Publication No. 2018-19489

By the way, even in the rated load range where ZVS can be sufficiently performed, the excitation current of the inductor added to compensate for switching loss flows, resulting in unnecessary power loss. In order to prevent the occurrence of power loss, it is also possible to add and control a switching element, for example. However, adding a switch element is not preferable because it increases the cost of the power supply device and increases the mounting area.

The present disclosure has been made in view of the above, and aims to provide a power supply device that can suppress increases in cost and increase in mounting area.

A power supply device according to an aspect of the present disclosure includes a first input terminal and a second input terminal into which a DC voltage is input, and a first switch connected in series between the first input terminal and the second input terminal. a third switch element and a fourth switch element connected in parallel with the first switch element and the second switch element and connected in series with each other, and a primary winding connected to the first switch element and a second switch element; a first transformer connected between a first node between the element and the second switch element and the second input terminal; and a first transformer whose primary winding is connected to the third switch element and the fourth switch element. a second transformer connected between a second node between the transformer and the second input terminal, the second transformer having a secondary winding connected in series with the secondary winding of the first transformer; A control unit that controls switching operations of an auxiliary inductor provided between the second node, the first switch element, the second switch element, the third switch element, and the fourth switch element. and.

The auxiliary inductor is configured based on a phase difference between an operation of a first arm including the first switch element and the second switch element and an operation of the second arm including the third switch element and the fourth switch element. It is preferable that the magnet be excited by

Preferably, the device further includes a capacitor connected in series with the auxiliary inductor between the first node and the second node.

A power supply device according to one embodiment of the present disclosure can suppress an increase in cost and an increase in mounting area.

FIG. 1 is a diagram illustrating an example of the configuration of a power supply device according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a power supply device according to a comparative example. FIG. 3 is a diagram showing the waveform of the current flowing through the auxiliary inductor when the power supply device according to the comparative example is operating at the rated load. FIG. 4 is a diagram for explaining a method for reducing power loss in a power supply device of a comparative example. FIG. 5 is a diagram for explaining a method for reducing power loss in a power supply device of a comparative example. FIG. 6 is a diagram illustrating the operation of the power supply circuit of FIG. 1. FIG. 7 is a diagram illustrating the operation of the power supply circuit of FIG. 1.

Embodiments of the present invention will be described in detail below based on the drawings. In the description of each figure below, the same or equivalent components as those in other figures are denoted by the same reference numerals, and the explanation thereof will be simplified or omitted. The present invention is not limited to each embodiment. Furthermore, the constituent elements of each embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Note that the configurations described below can be combined as appropriate. Further, the configuration may be omitted, replaced, or changed without departing from the gist of the invention.

The configuration of the power supply device according to the embodiment will be described using FIG. 1. FIG. 1 is a diagram illustrating an example of the configuration of a power supply device according to an embodiment.

The power supply device 1 includes a first input terminal 11 , a second input terminal 12 , a smoothing capacitor 13 , an isolated resonant converter 20 , a first output terminal 31 , a second output terminal 32 , and a smoothing capacitor 33 , a control section 100 , a current detection section 110 , and a storage section 120 .

A DC voltage is input to the first input terminal 11 and the second input terminal 12.

Smoothing capacitor 13 is electrically connected to first input terminal 11 and second input terminal 12 . The smoothing capacitor 13 smoothes the DC voltage input to the first input terminal 11 and the second input terminal 12. Smoothing capacitor 13 outputs the smoothed DC voltage to isolated resonant converter 20 .

The isolated resonant converter 20 includes a switch element Q ₁ as a first switch element, a switch element Q ₂ as a second switch element, a switch element Q ₃ as a third switch element, and a switch as a fourth switch element. It includes an element _Q4 , an auxiliary inductor La, a transformer TR1, a transformer TR2, and a diode bridge DB. Although the isolated resonant converter 20 will be described as a half-bridge type LLC converter, the present disclosure is not limited thereto. The isolated resonant converter 20 may be a full-bridge type LLC converter. Note that the transformer TR1 and the transformer TR2 may be combined into one transformer.

The switch element Q ₁ , the switch element Q ₂ , the switch element Q ₃ , and the switch element Q ₄ can be realized by, for example, N-channel field effect transistors. Note that each switch element may be realized by a silicon power device, a GaN power device, a SiC power device, an IGBT (Insulated Gate Bipolar Transistor), or the like.

The switch element Q ₁ and the switch element Q ₂ are electrically connected in series to each other between the first input terminal 11 and the second input terminal 12 .

The switch element Q ₃ and the switch element Q ₄ are electrically connected in series to each other between the first input terminal 11 and the second input terminal 12. Further, the series circuit of switch element Q ₃ and switch element Q ₄ is connected in parallel to the series circuit of switch element Q ₁ and switch element Q ₂ .

Auxiliary inductor La is an inductor for assisting the operation of ZVS. One end of the auxiliary inductor La is electrically connected to a node N1, which is a first node between the switch elements _Q1 and _Q2 , via the capacitor Ca. The other end of the auxiliary inductor La is electrically connected to a node N2, which is a second node between the switch elements _Q3 and _Q4 . Capacitor Ca is a capacitor for cutting direct current. One end of the auxiliary inductor La may be directly connected to the node N1 without providing the capacitor Ca.

The first transformer, the transformer TR1, has a primary winding 21, a secondary winding 22, and a core 23. The primary winding 21 and the secondary winding 22 are wound around the core 23. The transformer TR2, which is the second transformer, has a primary winding 24, a secondary winding 25, and a core 26. The primary winding 24 and the secondary winding 25 are wound around the core 26. One end of the secondary winding 22 of the transformer TR1 is electrically connected to one end of the secondary winding 25 of the transformer TR2. Therefore, the secondary winding 22 and the secondary winding 25 are connected in series.

The primary winding 21 includes a leakage inductance Lr1 and an excitation inductance Lm1. One end of the primary winding 21 is electrically connected to the node N1. The other end of the primary winding 21 is electrically connected to the second input terminal 12. The primary winding 21 includes a capacitor Cr1.

The primary winding 24 includes a leakage inductance Lr2 and an excitation inductance Lm2. One end of the primary winding 24 is electrically connected to the node N2. The other end of the primary winding 24 is electrically connected to the second input terminal 12. The primary winding 24 includes a capacitor Cr2.

Diode bridge DB performs full-wave rectification of the alternating current voltage generated in secondary winding 22. The diode bridge DB includes a first diode _D11 , a second diode _D12 , a third diode _D13 , and a fourth diode _D14 .

The anode of the first diode _D11 is electrically connected to one end of the secondary winding 22. The cathode of the first diode _D11 is electrically connected to the first output terminal 31.

The anode of the second diode _D12 is electrically connected to one end of the secondary winding 25. A cathode of the second diode D ₁₂ is electrically connected to the first output terminal 31 .

The anode of the third diode _D13 is electrically connected to the second output terminal 32. A cathode of the third diode _D13 is electrically connected to one end of the secondary winding 22.

The anode of the fourth diode D ₁₄ is electrically connected to the second output terminal 32 . The cathode of the fourth diode _D14 is electrically connected to one end of the secondary winding 25.

Smoothing capacitor 33 smoothes the output voltage output from diode bridge DB. Smoothing capacitor 33 is electrically connected between first output terminal 31 and second output terminal 32 .

The control unit 100 is realized by, for example, executing a program stored in a storage unit (not shown) by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc. using a RAM (Random Access Memory) or the like as a work area. be done. Further, the control unit 100 is a controller, and may be realized by, for example, an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

The control unit 100 controls switching operations of the switch element Q ₁ , the switch element Q ₂ , the switch element Q ₃ , and the switch element Q ₄ according to a control signal input from the outside. Specifically, the control unit 100 controls the switching elements Q1, _Q2 , _Q3 , and _Q3 based on the value of the current flowing through the primary winding 21 or the secondary winding 22. Controls switching operation with _Q4 . For example, the control unit 100 outputs a PWM (Pulse Width Modulation) signal to the switch element _Q1 , the switch element _Q2 , the switch element _Q3 , and the switch element _Q4 , and controls the switching operation of each switch element. control.

The control unit 100 transmits the input voltage input to the first input terminal ₁₁ and the second input terminal 12 to the transformer TR1 by controlling the switching operations of the switch element Q 1 and the switch element Q ₂ . Further, the control unit 100 transmits the input voltage input to the first input terminal 11 and the second input terminal 12 to the transformer TR2 by controlling the switching operations of the switch element Q ₃ and the switch element Q ₄ .

In the case of a rated load, the control unit 100 controls the switching elements Q ₁ , Q 2 , Q ₃ , and Q ₃ so that the phases of the operation of the arm 30 ₁ and the operation of the arm 30 ₂ match. Switching operation is performed on _Q4 . In addition, in the case of a light load, the control unit 100 controls the switch element Q ₁ , the switch element Q ₂ , the switch element Q ₃ , and the switch so that the operation of the arm 30 ₁ and the operation of the arm 30 ₂ are out of phase. Switching operation is performed on element _Q4 . _The control unit 100 controls the switch elements Q ₁ , Q 2 , Q ₃ , and the switches so that the phases of the operation of the arm 30 ₁ and the operation of the arm 30 ₂ are shifted by 180° in the case of no load. Switching operation is performed on element _Q4 . The output can be stopped by shifting the phase of the operation of the arm ₃₀₁ and the operation of the arm ₃₀₂ by 180 degrees.

The current detection unit 110 detects a current flowing through at least one of the primary winding 21 or 24, the secondary winding 22, or the secondary winding 25. The current detection section 110 outputs the current detection result to the control section 100.

The storage unit 120 stores various information. The storage unit 120 stores, for example, a predetermined threshold current. If the value of the current detected by the current detection unit 110 exceeds the threshold current value stored in the storage unit 120, it means that the power supply device 1 is operating under a high load.

Here, in order to facilitate understanding of the embodiment, a comparative example will be described.
[Comparative example power supply device]
FIG. 2 is a diagram illustrating the configuration of a power supply device 1a of a comparative example. _The power supply device 1a of the comparative example shown in FIG. 2 is different from the power supply device ₁ shown in FIG. In addition to a certain switch element Q ₃ and a fourth switch element Q ₄ , an auxiliary switch element is provided. That is, the power supply device 1a includes a switch element Q5 which is an auxiliary switch element corresponding to the _{switch element Q1, a switch element Q6 which is} an auxiliary switch element which corresponds to the switch element _Q2 , and an auxiliary switch corresponding to the switch element _Q3 . It has a switch element Q ₇ which is an element, and a switch element Q ₈ which is an auxiliary switch element corresponding to the switch element Q ₄ .

Further, the power supply device 1a includes an auxiliary inductor La1 and an auxiliary inductor La2. One end of the auxiliary inductor La1 is connected to a node N1 between the switch element _Q1 and the switch element _Q2 . The other end of the auxiliary inductor La1 is connected to a node N3, which is a third node between the switch elements _Q5 and _Q6 . One end of the auxiliary inductor La2 is connected to a node N2 between the switch elements _Q3 and _Q4 . The other end of the auxiliary inductor La2 is connected to a node N4, which is a fourth node between switch elements _Q7 and _Q8 .

The control unit 100a controls a switch element Q ₁ , a switch element Q ₂ , a switch element Q ₃ , a switch element Q ₄ , a switch element Q ₅ , a switch element Q ₆ , according to a control signal input from the outside. Controls switching operations with switch element Q ₇ and switch element Q ₈ .

In the power supply device 1a according to the comparative example, in order to assist the ZVS operation in the case of a light load, the phase of the gate voltage of the switch element _Q5 , which is an auxiliary switch element, is shifted from the phase of the gate voltage of the switch element _Q1 . Similarly, the phase of the gate voltage of switch element Q ₆ , which is an auxiliary switch element, is shifted from the phase of the gate voltage of switch element Q ₂ . This causes a potential difference between node N1 and node N2. Therefore, the energy of the auxiliary inductor La1 can be transmitted to the transformer TR1, so that the ZVS operation can be assisted in the case of a light load.

When shifting the phase as described above, even when the power supply device 1a is operating under a high load, the phases of the gate voltages of the switch element _Q5 and the switch element _Q6 are the same as that of the switch element _Q1 and the switch element _Q2, respectively. remains out of phase with the gate voltage. When the power supply device 1 is operating under a high load in this manner, there is no need to supply the current of the auxiliary inductor La1 to the transformer TR1, but the current continues to flow through the auxiliary inductor La1.

Similarly, in the power supply device 1a according to the comparative example, in order to assist the ZVS operation in the case of a light load, the phase of the gate voltage of the switch element _Q7 , which is an auxiliary switch element, is changed from the phase of the gate voltage of the switch element _Q3 . shift. Similarly, the phase of the gate voltage of switch element _Q8 , which is an auxiliary switch element, is shifted from the phase of the gate voltage of switch element _Q4 . This causes a potential difference between node N1 and node N2. Therefore, the energy of the auxiliary inductor La2 can be transmitted to the transformer TR2, so that the ZVS operation can be assisted in the case of a light load.

When shifting the phase as described above, even when the power supply device 1a is operating under high load, the phases of the gate voltages of switch element _Q7 and switch element _Q8 are the same as those of switch element _Q3 and switch element _Q4, respectively. remains out of phase with the gate voltage. When the power supply device 1 is operating under a high load in this way, there is no need to supply the current of the auxiliary inductor La2 to the transformer TR2, but the current continues to flow through the auxiliary inductor La2.

FIG. 3 is a diagram showing the waveform of the current flowing through the auxiliary inductor La1 when the power supply device 1a according to the comparative example is operating at the rated load. As shown in FIG. 3, for example, a current of about -0.4 [A] to about 0.4 [A] flows through the auxiliary inductor La, resulting in unnecessary power loss. In order to assist the ZVS operation in the case of a light load and to reduce power loss in the case of a rated load, the following control is performed, for example.

That is, the control unit 100a controls the switching element Q when the value of the current flowing through the primary winding 21 or the secondary winding 22 is below the threshold current value based on the detection result of the current detection unit 110. ₅ and switch element Q ₆ controls the phase of the gate voltage. Specifically, the control unit 100a controls the phase of the gate voltage of the switch element _Q5 to be shifted from the phase of the gate voltage of the switch element _Q1 . The control unit 100a may advance or delay the phase of the gate voltage of the switch element _Q5 from the phase of the gate voltage of the switch element _Q1 . Similarly, the control unit 100a controls the phase of the gate voltage of the switch element _Q6 to be shifted from the phase of the gate voltage of the switch element _Q2 .

By shifting the phases of the gate voltages of switch element Q ₁ and switch element Q ₅ and shifting the phase of gate voltages of switch element Q ₂ and switch element Q ₆ , a potential difference is generated between node N1 and node N2. Thereby, the energy of the auxiliary inductor La1 can be transmitted to the transformer TR, so that the ZVS operation can be assisted in the case of a light load.

Here, the processing of the control unit 100a when the power supply device 1a of the comparative example is operating at the rated load will be described using FIGS. 4 and 5. 4 and 5 are diagrams for explaining a method for reducing power loss in the power supply device 1a of the comparative example.

FIG. 4 shows a voltage waveform V _G2 of the gate voltage of the switch element Q ₂ and a voltage waveform V _G6 of the gate voltage of the switch element Q ₆ in FIG. In FIG. 4, the voltage waveform V _G2 is shown by a solid line, and the voltage waveform V _G6 is shown by a broken line. As shown in FIG. 4, when the value of the current flowing through the primary winding 21 or the secondary winding 22 exceeds the threshold current value, the control unit 100 controls the phase of the gate voltage of the switching element _Q6. is controlled to be synchronized with the phase of the gate voltage of switch element _Q2 . Similarly, when the value of the current flowing through the primary winding 21 or the secondary winding 22 exceeds the threshold current value, the control unit 100 controls the phase of the gate voltage of the switch element Q5 and the phase of the gate voltage of the switch element _Q5 . Control is performed so that the phase of the gate voltage of _Q1 is synchronized.

FIG. 5 shows a voltage waveform V _DS2 of the drain-source voltage of the switch element Q ₂ and a voltage waveform V _DS6 of the drain-source voltage of the switch element Q ₆ in FIG.

Ideally, by matching the phase of the gate voltage of switch element Q ₂ and the phase of the gate voltage of switch element Q ₆ , the phase of the drain-source voltage of switch element Q ₂ and the phase of the gate voltage of switch element Q ₆ can be matched. coincides with the phase of the drain-source voltage. Similarly, by matching the phase of the gate voltage of switch element _Q1 and the phase of the gate voltage of switch element _Q5 , the phase of the drain-source voltage of switch element _Q1 and the phase of the drain-source voltage of switch element _Q5 can be matched.・The phase of the voltage between sources matches. By matching the phase of the drain-source voltage of each switch element with the phase of the drain-source voltage of each corresponding switch element, the potential difference between node N1 and node N2 at both ends of auxiliary inductor La1 is reduced to 0. become. Therefore, no current flows through the auxiliary inductor La1.

The above description has been made regarding switch elements Q ₁ , Q ₂ , Q ₅ and Q ₆ with reference to FIGS. 4 and 5, but the same applies to switch elements Q ₃ , Q ₄ , Q ₇ and Q ₈ .

In the _power supply device 1a of the comparative example shown in FIG. The phase of the gate voltage and the phase of the gate voltage of switch element _Q2 are synchronized with the phase of the gate voltage of switch element _Q5 , which is an auxiliary switch element, and the phase of the gate voltage of switch element _Q6, which is an auxiliary switch element. Control. By doing so, the current flowing through the auxiliary inductor La1 can be made zero.

Similarly, in the power supply device 1a, when the value of the current flowing through either the primary winding 24 or the secondary winding 25 of the transformer TR2 exceeds a predetermined threshold, the phase of the gate voltage of the switch element _Q3 And the phase of the gate voltage of switch element _Q4 is controlled so as to be synchronized with the phase of the gate voltage of switch element _Q7 and the phase of the gate voltage of switch element _Q8 . By doing so, the current flowing through the auxiliary inductor La2 can be made zero.

In the power supply device 1a of the comparative example, four auxiliary switch elements, namely, switch element Q ₅ , switch element Q ₆ , switch element Q ₇ and switch element Q ₈ are required. Also, two auxiliary inductors La1 and La2 are required. For this reason, in the power supply device 1a of the comparative example, the number of components increases, resulting in an increase in cost and an increase in mounting area.

[Power supply device of embodiment]
Returning to FIG. 1, in the power supply device 1 according to the present embodiment, a series circuit of an auxiliary inductor La and a capacitor Ca is connected between a node N1 and a node N2. That is, the midpoint (node N1) of the first arm 30 ₁ that includes the switch element Q ₁ and the switch element Q ₂ , and the midpoint (node N1) of the second arm 30 ₂ that includes the switch element Q ₃ and the switch element Q ₄ . A series circuit of an auxiliary inductor La, which is a ZVS auxiliary inductor, and a capacitor Ca is connected between the ZVS auxiliary inductor and the capacitor Ca. Therefore, based on the phase difference between the operation of the first arm 30 ₁ including the switch element Q ₁ and the switch element Q ₂ and the operation of the second arm 30 ₂ including the switch element Q ₃ and the switch element Q ₄ , , the auxiliary inductor La is excited.

6 and 7 are diagrams illustrating the operation of the power supply device 1 shown in FIG. 1. FIG. 6 is a diagram illustrating the operation of the power supply device 1 of FIG. 1 in the case of no load. In FIG. 6, the phase difference between voltage waveform V _G2 and voltage waveform V _G4 is 180°, and the phase difference between voltage waveform V _DS2 and voltage waveform V _DS4 is 180°. In the case of no load, a phase difference occurs between the operation of the first arm ₃₀₁ and the operation of the second arm ₃₀₂ , the auxiliary inductor La is excited, and the current _ILa flows through the auxiliary inductor La. The current I _La flowing through the auxiliary inductor La allows each switch element, that is, switch element Q ₁ , switch element Q ₂ , switch element Q ₃ , and switch element Q ₄ to perform a ZVS operation.

FIG. 7 is a diagram illustrating the operation of the power supply device 1 of FIG. 1 at the rated load. In FIG. 7, the phase difference between voltage waveform V _G2 and voltage waveform V _G4 is 0°, and the phase difference between voltage waveform V _DS2 and voltage waveform V _DS4 is 0°. In the case of the rated load, no current flows through the auxiliary inductor La because there is no phase difference between the operation of the first arm 30 ₁ and the operation of the second arm 30 ₂ . That is, as shown in FIG. 7, the current _ILa flowing through the auxiliary inductor La is 0 [A].

In the power supply device 1a of the comparative example shown in FIG. 2, it is necessary to provide four auxiliary switch elements, that is, switch element _Q5 , switch element _Q6 , switch element _Q7 , and switch element _Q8 . On the other hand, according to the power supply device 1 shown in FIG. 1, there is no need to provide these auxiliary switch elements. Therefore, the number of switch elements does not increase, and it is possible to suppress an increase in cost and an increase in mounting area.

In the power supply device 1a of the comparative example shown in FIG. 2, two auxiliary inductors La1 and La2 are provided. In contrast, according to the power supply device 1 shown in FIG. 1, one auxiliary inductor La is sufficient. Therefore, it is possible to suppress an increase in cost and an increase in mounting area.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited by the contents of these embodiments. Furthermore, the above-mentioned components include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that are in a so-called equivalent range. Furthermore, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the constituent elements can be made without departing from the gist of the embodiments described above.

1, 1a Power supply device 11 First input terminal 12 Second input terminal 13 Smoothing capacitor 20 Isolated resonant converter 21, 24 Primary windings 22, 25 Secondary windings 23, 26 Core 31 First output terminal 32 Second Output terminal 33 Smoothing capacitor 100, 100a Control unit 110 Current detection unit 120 Storage unit 30 ₁ First arm 30 ₂ Second arm Ca, Cr1, Cr2 Capacitor D ₁₁ First diode D ₁₂ Second diode D ₁₃ Third diode D ₁₄ Fourth diode DB Diode bridge La, La1, La2 Auxiliary inductor Lm1, Lm2 Excitation inductance Lr1, Lr2 Leakage inductance N1, N2, N3, N4 Node Q ₁ , Q ₂ , Q ₃ , Q ₄ , Q ₅ , Q ₆ , _Q7 , _Q8 switch elements TR1, TR2 transformer

Claims (3)

a first input terminal and a second input terminal into which a DC voltage is input;
a first switch element and a second switch element connected in series between the first input terminal and the second input terminal;
a third switch element and a fourth switch element connected in parallel with the first switch element and the second switch element and connected in series with each other;
a first transformer having a primary winding connected between a first node between the first switch element and the second switch element and the second input terminal;
A primary winding is connected between a second node between the third switch element and the fourth switch element and the second input terminal, and a secondary winding is connected to the second input terminal of the first transformer. a second transformer connected in series with the line;
an auxiliary inductor provided between the first node and the second node;
a control unit that controls switching operations of the first switch element, the second switch element, the third switch element, and the fourth switch element;
Equipped with
power supply. The auxiliary inductor is configured based on a phase difference between an operation of a first arm including the first switch element and the second switch element and an operation of the second arm including the third switch element and the fourth switch element. is excited by
The power supply device according to claim 1. further comprising a capacitor connected in series with the auxiliary inductor between the first node and the second node;
The power supply device according to claim 1 or claim 2.

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